Finding a Common Denominator When One is a Multiple of the Other
Finding a common denominator when one denominator is a multiple of the other is a Grade 5 math skill in enVision Mathematics, Chapter 7: Use Equivalent Fractions to Add and Subtract Fractions. If one denominator already divides evenly into the other, the larger denominator can serve as the common denominator directly, simplifying the process of creating equivalent fractions for addition and subtraction.
Key Concepts
If one denominator, $d 2$, is a multiple of another denominator, $d 1$, then the larger denominator, $d 2$, can be used as a common denominator.
Common Questions
How do you find a common denominator when one denominator is a multiple of the other?
Use the larger denominator as the common denominator. Multiply the numerator and denominator of the fraction with the smaller denominator to make equivalent fractions.
What is the common denominator for 1/3 and 1/6?
6 is a multiple of 3, so 6 is the common denominator. Convert 1/3 to 2/6, then add or subtract with 1/6.
Why is it easier when one denominator is a multiple of the other?
You only need to convert one fraction, not both. This saves a step and reduces the chance of making errors.
Where is finding common denominators taught in enVision Grade 5?
Chapter 7: Use Equivalent Fractions to Add and Subtract Fractions in enVision Mathematics, Grade 5.
What if neither denominator is a multiple of the other?
Then you need to find the least common multiple (LCM) of both denominators and convert both fractions to equivalent fractions with that LCM as the denominator.